WO2009096201A1

WO2009096201A1 - Inner joint member for constant velocity universal joint, method of producing the same, and constant velocity universal joint

Info

Publication number: WO2009096201A1
Application number: PCT/JP2009/050002
Authority: WO
Inventors: Hiromitsu Hamaguchi
Original assignee: Ntn Corporation
Priority date: 2008-02-01
Filing date: 2009-01-05
Publication date: 2009-08-06
Also published as: EP2251559B1; US8317629B2; CN101918728A; JP5202975B2; US20110118036A1; JP2009185831A; EP2251559A1; EP2251559A4; CN101918728B

Abstract

An inner joint member for a constant velocity universal joint allows a cutting tool to be used for longer life and enables the joint to be produced at reduced production costs. The inner joint member is mounted in an outer joint member (3) and has a plurality of ball track grooves (5) formed in an outer diameter surface (4) of the inner joint member. The surface roughness of a spherical surface on the end (A) side which corresponds to a region from the axial center (15) of the outer diameter surface (4) till the opening side of the outer joint member (3) is set greater than the surface roughness of a spherical surface on the end (B) side which corresponds to a region from the axial center (15) of the outer diameter surface (4) till the deep end side of the outer joint member (3).

Description

Inner joint member for constant velocity universal joint, manufacturing method thereof, and constant velocity universal joint

The present invention relates to an inner joint member for a constant velocity universal joint, and is used in a power transmission system of an automobile or various industrial machines. The inner joint member of a fixed type constant velocity universal joint using a ball as a rolling element, The present invention relates to a manufacturing method and a constant velocity universal joint including the inner joint member.

Constant velocity universal joints generally include an outer joint member having a track groove formed on the inner diameter side, an inner joint member having a track groove formed on the outer diameter side, and a track groove and an inner joint member of the outer joint member. And a cage for holding the ball interposed between the inner diameter surface of the outer joint member and the outer diameter surface of the inner joint member. .

In such a constant velocity universal joint, the inner surface of the outer ring as the outer joint member and the outer surface of the inner ring as the inner joint member are in contact with the cage, and therefore are cut after the thermosetting (quenching) (quenching). Dimensional accuracy and surface roughness are ensured by cutting steel) (Patent Document 1). As described in Patent Document 1, when the inner ring is cut after quenching, the surface roughness (surface roughness) of the outer diameter surface is the same throughout the entire area from one end side to the other end side of the outer diameter surface. ing.
JP 2002-188653 A

However, when machining the outer diameter surface of the inner ring by hardened steel cutting, it is generally cut from the end side corresponding to the back side of the outer ring to the end side corresponding to the inlet side of the outer ring. Accordingly, the surface roughness decreases from the center of the outer diameter surface of the inner ring to the end side corresponding to the inlet side of the outer ring. If the surface roughness can no longer satisfy the specified value from the center of the outer diameter surface to the end portion corresponding to the inlet side of the outer ring, the tool reaches the end of its service life at that time. In particular, if the tool is expensive, the tool life has a great influence on the production cost, so that it is required to extend the tool life.

In view of such circumstances, the present invention includes an inner joint member for a constant velocity universal joint capable of extending the life of a cutting tool and reducing the production cost, a manufacturing method thereof, and the inner joint member. Provide constant velocity universal joints.

An inner joint member for a constant velocity universal joint according to the present invention is an inner joint member for a constant velocity universal joint that is incorporated in an outer joint member and has a plurality of ball track grooves formed on the outer diameter surface. The spherical surface roughness on the end side corresponding to the back side of the outer joint member from the center in the direction is different from the spherical surface roughness on the end side corresponding to the opening side of the outer joint member from the axial center of the outer diameter surface. It has been made.

According to the inner joint member for a constant velocity universal joint of the present invention, the spherical surface roughness between the end side corresponding to the back side of the outer joint member and the end side corresponding to the opening side from the axial center of the outer diameter surface. By varying the degree, either can be finished rough. Thereby, in the rough range, the finishing process by the cutting tool can be roughly finished. That is, the tool life criterion can be relaxed in this rough range.

The spherical surface roughness on the end side corresponding to the opening side of the outer joint member from the axial center of the outer diameter surface is determined on the end side corresponding to the inner side of the outer joint member from the axial center of the outer diameter surface. It is preferable to make it rougher than the spherical surface roughness. This is because the track groove of the outer joint member opens to the inlet side (opening side), and therefore, on the outer diameter surface of the inner joint member, the spherical surface on the end side corresponding to the opening side of the outer joint member from the axial center. This is because even if the surface roughness is rough, the influence on the function of the constant velocity universal joint is small.

The spherical surface roughness of the end side corresponding to the opening side of the outer joint member from the axial center of the outer diameter surface is R1, and the end portion corresponding to the inner side of the outer joint member from the axial center of the outer diameter surface R2 <R1 <2 × R2 when the spherical surface roughness on the side is R2, or the spherical surface on the end side corresponding to the back side of the outer joint member from the axial center of the outer diameter surface The roughness can be Ra 0.8 or less.

The method for producing an inner joint member for a constant velocity universal joint according to the present invention is a method for producing an inner joint member for a constant velocity universal joint that is incorporated in an outer joint member and has a plurality of ball track grooves formed on an outer diameter surface thereof. The cutting tool is moved from the end side corresponding to the back side of the outer joint member of the outer diameter surface to the end side corresponding to the opening side of the outer joint member to cut the outer diameter surface, and the outer diameter The spherical surface roughness on the end side corresponding to the opening side of the outer joint member from the axial center of the surface is the spherical surface roughness on the end side corresponding to the inner side of the outer joint member from the axial center of the outer diameter surface. It is a method of making it rougher than the degree.

Since the spherical surface roughness on the end side corresponding to the opening side of the outer joint member from the center in the axial direction of the outer diameter surface is formed to be rough, the tool life criterion can be relaxed in this rough range. .

The constant velocity universal joint of the present invention includes an outer joint member in which a plurality of ball track grooves are formed on an inner diameter surface, an inner joint member in which a plurality of ball track grooves are formed on an outer diameter surface, and a ball of the outer joint member. A plurality of balls that are interposed between the track grooves and the ball track grooves of the inner joint member and transmit torque; and are interposed between the inner diameter surface of the outer joint member and the outer diameter surface of the inner joint member. In the constant velocity universal joint provided with the cage for holding the ball, the spherical surface roughness of the end side corresponding to the opening side of the outer joint member from the axial center of the outer diameter surface of the inner joint member is It is made rougher than the spherical surface roughness on the end side corresponding to the back side of the outer joint member from the axial center of the radial surface.

Since the spherical surface roughness on the end side corresponding to the opening side of the outer joint member from the center in the axial direction of the outer diameter surface of the inner joint member is rough, the tool life criterion is relaxed in this rough range. can do.

In the inner joint member for a constant velocity universal joint according to the present invention, finishing with a cutting tool can be roughly finished in a rough range. For this reason, in the rough range, the tool life criterion is relaxed, the life of the cutting tool can be extended, and the production cost can be reduced.

Further, since the track groove of the outer joint member opens to the inlet side (opening side), the spherical surface roughness on the end side corresponding to the inlet side (opening side) from the axial center of the outer diameter surface of the inner joint member is reduced. Even if the degree is rough, there is little influence on the function of the constant velocity universal joint. For this reason, on the outer diameter surface of the inner joint member, the spherical surface roughness on the end side corresponding to the opening side of the outer joint member is preferably roughened from the center in the axial direction.

In particular, the spherical surface roughness on the end side corresponding to the opening side of the outer joint member from the axial center of the outer diameter surface of the inner joint member is R1, and from the axial center of the outer diameter surface to the inner side of the outer joint member. By setting R2 <R1 <2 × R2 when the corresponding end surface spherical surface roughness is R2, the tool life can be greatly extended.

Further, the spherical surface roughness on the end side corresponding to the back side of the outer joint member from the axial center of the outer diameter surface of the inner joint member is set to Ra 0.8 or less, which is given to the function of the constant velocity universal joint. The influence can be extremely reduced.

Embodiments of an inner joint member for a constant velocity universal joint according to the present invention will be described with reference to FIGS.

FIG. 2 shows a constant velocity universal joint using the inner joint member for constant velocity universal joint according to the present invention. The constant velocity universal joint includes an outer ring 3 as an outer joint member in which a ball track groove 2 (hereinafter simply referred to as a track groove 2) is formed on the inner diameter surface 1, and a ball track groove 5 on the outer diameter surface 4. Torque is transmitted by interposing between the inner ring 6 as an inner joint member formed with the inner ring member (hereinafter simply referred to as the track groove 5) and the track groove 2 of the outer ring 3 and the track groove 5 of the inner ring 6. And a cage 8 that is interposed between the inner diameter surface 1 of the outer ring 3 and the outer diameter surface 4 of the inner ring 6 and holds the balls 7. The outer ring 3 includes a bowl-shaped mouse portion 3a having a track groove 2 and a stem portion 3b protruding from the bottom of the mouse portion 3a.

The shaft 11 is inserted into the center hole (inner diameter hole) 12 of the inner ring 6 and is fitted with a spline, and the torque can be transmitted between the two by the spline fitting. The shaft 11 is prevented from coming off from the inner ring 6 by a retaining ring 13.

The center of curvature O1 of the track groove 2 of the outer ring 3 is shifted from the joint center O in the axial direction toward the opening side of the outer ring 3, and the center of curvature O2 of the track groove 5 of the inner ring 6 is shifted from the joint center O to the outer ring 3 in the axial direction. The track groove 2 is provided on the back side opposite to the center of curvature O1 by an equal distance f.

The outer diameter surface 4 of the inner ring 6 is a cut surface after quenching. That is, when the inner ring 6 is made of a steel material such as medium carbon steel, the outer diameter surface 4 and the track groove 5 are cut after thermosetting (for example, induction hardening). Here, the induction hardening is hardening in which a member to be cured is placed between coils through which a high-frequency current passes, and the surface of the member to be cured is heated by Joule heat accompanying eddy current.

In this case, as shown in FIG. 1, the outer diameter surface 4 of the inner ring 6 is referred to as an end A corresponding to the opening side of the outer ring 3 from the axial center 15 (hereinafter simply referred to as an end A corresponding to the opening side). And a range H2 of an end B corresponding to the back side of the outer ring 3 from the axial center 15 (hereinafter sometimes simply referred to as an end B corresponding to the back side). The roughness (surface roughness) is made different. In this embodiment, the spherical surface roughness in the range H1 is made rougher than the spherical surface roughness in the range H2. Specifically, when the surface roughness of the range H1 is R1, and the surface roughness of the range H2 is R2, R2 <R1 <2 × R2. Further, the surface roughness R2 in the range H2 is set to Ra 0.8 or less.

Here, the surface roughness (surface roughness) is the centerline average roughness, and the roughness curve is folded back from the centerline, and the area obtained by the roughness curve and the centerline is divided by the measured length. Value is expressed in micrometers (μm).

By the way, as shown in FIG. 1, the cutting (grinding) of the outer diameter surface 4 of the inner ring 6 is performed by opening the blade of the tool 16 from the end B side corresponding to the inner side of the outer diameter surface 4 as indicated by an arrow. It moves to the end A side corresponding to the side. At this time, the surface roughness in the range H1 from the axial center 15 to the end A side may be rougher than the surface roughness in the range H2 from the axial center 15 to the end B, so the cutting tool in the range H1 Finishing with can be finished rough.

In the present invention, since the finishing process by the cutting tool can be roughly finished in the range H1 on the end A side corresponding to the opening side from the axial center 15, the wear of the cutting tool can be reduced. Thereby, the lifetime of the cutting tool can be extended, and the production cost can be reduced.

Contrary to the embodiment, the spherical surface roughness in the range H2 on the end B side corresponding to the back side from the axial center 15 is the range on the end A side corresponding to the opening side from the center 15 in the axial direction. You may make it rougher than the spherical surface roughness in H1. However, since the track groove 2 of the outer ring 3 opens to the inlet side (opening side), the spherical surface roughness in the range H1 on the end A side corresponding to the opening side from the axial center 15 is set to the axial center 15. The roughness of the spherical surface roughness in the range H2 on the end B side corresponding to the rear side from the rear side has less influence on the function of the constant velocity universal joint. Therefore, as in the embodiment described with reference to FIG. 1, it is preferable to make the spherical surface roughness in the range H1 from the axial center 15 to the end A side (rather than the spherical surface roughness in the range H2).

In particular, the spherical surface roughness on the end A side corresponding to the opening side from the axial center 15 of the outer diameter surface 4 is R1, and the end B side corresponding to the inner side from the axial center 15 of the outer diameter surface 4 is R1. By setting R2 <R1 <2 × R2 when the spherical surface roughness is R2, the tool life can be greatly extended. Further, by setting the spherical surface roughness on the end B side corresponding to the back side from the axial center 15 of the outer diameter surface 4 to Ra 0.8 or less, the influence on the function of the constant velocity universal joint is extremely small. can do. When the spherical surface roughness on the end B side corresponding to the back side from the axial center 15 of the outer diameter surface 4 exceeds Ra 0.8, the outer ring surface becomes too rough and the inner ring 6 is used to make a constant velocity universal joint. If configured, there is a possibility that the operating angle cannot be taken smoothly.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, in FIG. 2, a bar field type (BJ) is shown as a constant velocity universal joint, but other fixed type constant velocity universal joints such as an undercut free type (UJ) may be used. Further, the number of balls 7 can be arbitrarily set. In particular, the number of balls 7 can be set in the range of 3 to 8, but is not limited thereto. In addition, the hardening process may be a process such as carburizing and quenching other than induction hardening.

Incidentally, the track groove 5 of the inner ring 6 is also cut after quenching (quenched steel cutting). The surface roughness of the track groove 5 is preferably set to Ra 0.8 or less, like the outer diameter surface 4.

Fig. 3 shows the relationship between the number of machining and surface roughness that can be machined with one cutting tool. When the entire outer diameter surface 4 of the inner ring 6 has the same surface roughness, when the number of processing exceeds about 500, the surface roughness on the end A side (see FIG. 1) corresponding to the opening side of the outer diameter surface 4. Becomes coarse. Thus, the tool life is reached when the surface roughness on the end A side corresponding to the opening side cannot be secured to the same surface roughness as the end B side or axial center corresponding to the back side. . However, as in the present invention, when the surface roughness on the end A side corresponding to the opening side may be rougher than the surface roughness on the end B side corresponding to the back side, the tool life is, for example, The number of processes can be extended to about 1000. In FIG. 3, ● indicates the surface roughness at the axial center 15, ■ indicates the surface roughness on the end B side corresponding to the back side, and ▲ indicates the end corresponding to the inlet side (opening side). The surface roughness on the part A side is shown.

It is principal part sectional drawing of the inner joint member for constant velocity universal joints which shows embodiment of this invention. It is sectional drawing of the constant velocity universal joint which uses the said inner joint for constant velocity universal joints. It is a graph which shows the relationship between surface roughness and the lifetime of a cutting tool.

Explanation of symbols

3 outer ring 4 outer diameter surface 5 ball track groove 6 inner ring 15 center in the axial direction A end corresponding to the opening side of the outer ring B end corresponding to the rear side of the outer ring

Claims

In the inner joint member for a constant velocity universal joint incorporated in the outer joint member and formed with a plurality of ball track grooves on the outer diameter surface,
The spherical surface roughness on the end side corresponding to the back side of the outer joint member from the axial center of the outer diameter surface, and the end side corresponding to the opening side of the outer joint member from the axial center of the outer diameter surface. An inner joint member for a constant velocity universal joint, characterized by having different spherical surface roughness.
The spherical surface roughness on the end side corresponding to the opening side of the outer joint member from the axial center of the outer diameter surface is determined on the end side corresponding to the inner side of the outer joint member from the axial center of the outer diameter surface. The inner joint member for a constant velocity universal joint according to claim 1, wherein the inner joint member is rougher than the spherical surface roughness.
The spherical surface roughness of the end side corresponding to the opening side of the outer joint member from the axial center of the outer diameter surface is R1, and the end portion corresponding to the inner side of the outer joint member from the axial center of the outer diameter surface The inner joint member for a constant velocity universal joint according to claim 2, wherein R2 <R1 <2 × R2 is satisfied when the spherical surface roughness on the side is R2.
The inner joint member for a constant velocity universal joint according to claim 3, wherein the spherical surface roughness of the end side corresponding to the inner side of the outer joint member from the axial center of the outer diameter surface is Ra 0.8 or less.
In the method of manufacturing an inner joint member for a constant velocity universal joint that is incorporated into the outer joint member and has a plurality of ball track grooves formed on the outer diameter surface thereof,
The cutting tool is moved from the end side corresponding to the back side of the outer joint member of the outer diameter surface to the end side corresponding to the opening side of the outer joint member to cut the outer diameter surface, and the outer diameter The spherical surface roughness on the end side corresponding to the opening side of the outer joint member from the axial center of the surface is the spherical surface roughness on the end side corresponding to the inner side of the outer joint member from the axial center of the outer diameter surface. The manufacturing method of the inner joint member for constant velocity universal joints characterized by making rougher than degree.
An outer joint member having a plurality of ball track grooves formed on the inner diameter surface, an inner joint member having a plurality of ball track grooves formed on the outer diameter surface, a ball track groove of the outer joint member, and a ball of the inner joint member A plurality of balls interposed between track grooves for transmitting torque; and a cage for holding the balls interposed between an inner diameter surface of the outer joint member and an outer diameter surface of the inner joint member. In a constant velocity universal joint,
The spherical surface roughness on the end side corresponding to the opening side of the outer joint member from the axial center of the outer diameter surface of the inner joint member corresponds to the inner side of the outer joint member from the axial center of the outer diameter surface. A constant velocity universal joint characterized in that it is rougher than the spherical surface roughness on the end side.